Hollow weave air bag

Abstract

A hollow weave air bag, a configuration of a boundary line between a hollow portion (6) and a peripheral portion (4) of a single layer weave bonding band of which is a curve obtained by that an optional point on an equation L=R(1+P/2×cos 4θ) draws by changing an angle θ, wherein: L stands for a length of a straight line between a center (c) of a hollow portion (6) and the boundary line (7); θ stands for an angle (radian) formed between a warp axis of a woven fabric and a straight line connecting an optional point (A) on the boundary line to a center (C) of the hollow portion (6); R stands for a mean value of a radius of a circumscribed circle and a radius of a inscribed circle; P stands for a ratio of a difference between the radius of the circumscribed circle and the radius of the inscribed circle against the mean radius R; O<P≦0.2 A hollow weave air bag having no sewn portion on the peripheral edge and having an extremely high withstanding pressure and a high reliability can be obtained in accordance with the present invention.

We claim: 
     
       1. A hollow weave air bag having a peripheral portion of a hollow portion which is bound by a single layer weave binding band, characterized in that a boundary line between the peripheral portion and the single layer weave binding band is formed with different lengths from a center of the hollow portion to the boundary line in such a manner that the length has a maximum value in a warp direction and a weft direction of the hollow weave air bag and a minimum value in a bias direction thereof, and is further formed substantially along a wavy continuous curve expressed by the following equation between a circumscribed circle and an inscribed circle of the boundary line:   L=R (1+P/2×cos 4θ)                             (1)       O<P≦0.2                                             (2)     wherein R stands for a mean value of a radius of the circumscribed circle and a radius of the inscribed circle;   P stands for a ratio of a difference between the radius of the circumscribed circle and the radius of the inscribed circle against the mean radius R;   θ stands for an angle measured in a clockwise direction from the warp direction;   L stands for a length from the center C of the hollow portion to the boundary line at the angle θ.   
     
     
       2. A hollow weave air bag according to claim 1, characterized in that lengths of straight lines within said boundary line in plan view extending through a center of the hollow portion of said air bag are substantially equal to each other in a warp direction, in a weft direction and in two bias directions, when said air bag is expanded at an internal pressure of 0.3 kgf/cm 2 . 
     
     
       3. A hollow weave air bag according to claim 1, characterized in that an opening for attaching a gas generator is arranged in the hollow portion of said air bag. 
     
     
       4. A hollow weave air bag according to claim 1, characterized in that a resin layer is provided on at least part of said air bag. 
     
     
       5. A hollow weave air bag according to claim 1, characterized in that at least a part of said single layer weave binding band is formed by a matt weave. 
     
     
       6. A hollow weave air bag according to claim 5, characterized in that a weave of an area adjacent to the boundary line in the single layer weave binding band is a matt weave, and an area outside of said area formed by the matt weave is formed by a weave in which a warp and a weft is constituted by a weave having a lower restriction compared with that of the matt weave.